(a) Field of the Invention
This invention generally relates to a safety hook and attachment system for connecting the safety hook to a harness.
More particularly, but not by way of limitation, to a hook with a gate that prevents unwanted release of the hook and allows the gate to cooperate with the hook in a synergistic manner.
(b) Discussion of Known Art
There is a large variety of safety hooks or xe2x80x9ctie backxe2x80x9d snap hooks that are designed for use as safety equipment. These hooks typically include a J-shaped hook portion that includes a gate that closes the mouth of the hook in order to prevent the inadvertent release of the hook.
The primary purpose of these hooks is to tether a worker to a support structure in order to prevent an unrestrained fall to the ground. The safety hooks are typically used as part of a lanyard that includes a shock absorber or dampening mechanism. One end of the lanyard is attached by way of a safety hook to the back of a harness, while the other end of the lanyard is attached to some sort of support structure, such as a crane, a section of steel or rebar, or other attachment point specifically provided for restraining a fall.
Because of the variety of attachment points and work condition present during an instance where the safety hook and fall arrest systems must be deployed, the actual fall path and restrain conditions are rather unpredictable. Thus, the loading on a safety hook can vary depending on what occurs during the fall. For example, some fall conditions can cause the entire load from the fall to be reacted on the gate of the hook, which is typically the weakest portion of the hook. In order to ensure that the gate does not fail, safety hooks must have gates that are capable of resisting the loads from the fall without opening into or out of the mouth of the hook.
Thus, the safety hooks, also referred to as tie back snap hooks, are frequently used in personal fall protection applications where anchorage connectors are not readily available. A tie back snap enables a worker to loop the lanyard that is connected to the snap around a pipe or beam and then snap it back onto itself. This enables the worker to use items such as pipes in a pipe rack or I-beams and other structures in building steel as anchorage tie off points where no other types of anchorage connections exists. Currently tie back applications are performed in two ways. In the first a D-ring is attached to the lanyard with a slip buckle that is positioned halfway between the snap end and the shock absorber end of the lanyard. The worker can then loop the lanyard over a pipe or beam and connect the snap into the D-ring. The D-ring location is then adjusted to provide a snug fit around the pipe or beam. With this application a standard double action single locking snap can be used to create a tie back application. In the second application the lanyard is looped over the pipe or beam and then the snap is connected or snapped back around the lanyard itself This type of application has several inherent problems.
The first problem is that the lanyard webbing can lie across the inside of the snap gate. In a fall arrest the lanyard tension could put as much as 5000-lb. of load on the snap gate. Standard snap gates are designed according to OSHA regulation to withstand only a 350-lb. load. Therefore standard, double action, single locking snaps will not work for this type of application. Another danger with the use of snap hooks is that a snap, when looped over an I-beam with the edge of the gate against the flange of the I-beam, can fail by forces on the gate which can open by the due to the action of the I-beam pressing against the gate during fall arrest. For these reasons tie back snaps must be designed so that the gate will take a 5000-lb. load without failure in any direction, not the 350-lb. load typical in standard locking snap hooks. Some manufacturers have designed snap hooks that meet these requirements. Typically these snaps are much larger, must have forged rather than stamped steel gates, and must use much larger and stronger hinge pins. All of which adds greatly to the cost and weight of the product.
It has been discovered that the problems left unanswered by known art can be solved by providing a snap-hook comprising:
A J-shaped body having a shank portion that includes a first end and a second end, the body further having a concave portion and a nose, the concave portion extending from the second end of the shank and terminating in the nose;
A gate that is pivotable about a pivot point that is near the first end of the shank;
A movable locking pin located near the second end of the shank;
At least one parallel bar that is generally parallel to the shank and extends along the shank;
A movable thumb grip that when moved urges the parallel bar to move the locking pin;
The locking gate further having a recessed portion positioned near the second end of the shank and a closure portion positioned near the nose of the hook body, the closure portion and the recessed portion being at about the same distance from the pivot point, the recessed portion being adapted to cooperate with the locking pin so that when the locking pin is moved by the parallel bar the gate is released so that the gate can pivot about the pivot point.
The present invention relates to an improved method of constructing a tie back snap for fall arrest applications that can be produced using existing manufacturing technology, can be made light weight, can be produced with a stamped steel gate, can be produced so that it can be snapped directly to its"" own. lanyard webbing without the possibility of the webbing being able to slip behind the gate to cause failure under load and can be produced at a cost no higher than existing standard locking snap hooks.
The present invention relates to a new and unique method of designing a locking anchorage snap so that it can be tied (or snapped) back onto its own lanyard in a manner that will not damage or cut the lanyard nor cause damage to the snap itself. Additionally, this patent relates to a method to lock and unlock the snap gate so that it reduces the applied gate loads. Additionally, this patent relates to a new and unique method of designing a snap gate so that it is impossible for the lanyard to apply outward forces to the tie back snap gate when the snap is connected back to its own lanyard. Additionally, this patent applies to a method used to prevent rollout (accidental disengagement) of the locking snap.
The method comprises:
a. A forged steel snaphook body
b. A stamped or formed steel locking gate
c. A stamped or formed steel gate lock
d. A protrusion in the forged hook body between the gate and thumb grip to prevent rollout
e. A thumb grip to release the gate lock
f. A locking pin to lock the gate under load
g. A flat widened portion of the forged snap hook body to relieve and distribute tension in the webbing during fall arrest.
h. A method to arrange the geometry and shape of the gate so that it is impossible for the webbing to be positioned behind the gate when the gate is closed.
l. A method to soften the edge of the snap to prevent damage to the webbing while moving through the snap.
j. A method in the engagement between the locking pin and the gate so that the gate cannot be unlocked while being loaded
k. A method to arrange the geometry between the gate and the locking pin so that the required locking force is always less than the load applied to the gate during fall arrest.
In another aspect this invention relates to the locking method of the tie back snaphook. This unique locking method required 2 separate and distinct motions to unlock the gate. First the thumb grip on the top of the snaphook must be rotated with the thumb in a backward motion towards the eye of the snaphook. This moves the locking pin at the front of the gate forward releasing the pin from its engagement with the gate. Next the index finger is used to pull on the gate grip to rotate it backwards also towards the eye of the snap hook. This opens the gate allowing the webbing to pass through to the inside of the snap. Releasing the thumb grip and the gate grip simultaneously allows the gate to rotate under spring load back to its"" closed position. Once in the closed position the thumb grip will rotate back under spring pressure until the locking pin is positioned firmly under the gate locking it into position.
It should also be understood that while the above and other advantages and results of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings, showing the contemplated novel construction, combinations and elements as herein described, and more particularly defined by the appended claims, it should be clearly understood that changes in the precise embodiments of the herein disclosed invention are meant to be included within the scope of the claims, except insofar as they may be precluded by the prior art.